Which is better between these games.

Call of Duty World At War, Gears of War 2, Fallout 3, or Guitar Hero World Tour.

I am seriously having a hard time trying to decide which one to get ):

any flaws about any of them that would be good knowledge for me?

Gears of War 2.

Well I really like the concept of Fallout 3, and most of my friends have Gears 2.

But the 4 player co-op, zombie mode, and the ability to earn xp in 4 player co-op in WaW makes me want the game badly o:

Gears 2 if you're looking for a multiplayer game.

Fallout 3 for a single player experience.

CoD5 - will have good Campaign, good Multiplayer

GoW2 - good Campaign, horrible Multiplayer

Fallout - good Campaign, no Multiplayer, only a good rent, can beat it in 3 days

GHWT - i don't play those games